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Jia-Feng Wu, M.D. Division of Gastroenterology, Department of Pediatrics, National Taiwan University Children Hospital.

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Presentation on theme: "Jia-Feng Wu, M.D. Division of Gastroenterology, Department of Pediatrics, National Taiwan University Children Hospital."— Presentation transcript:

1 Jia-Feng Wu, M.D. Division of Gastroenterology, Department of Pediatrics, National Taiwan University Children Hospital

2 + Impedance measurement is used to show the bolus transit in the esophagus. + Traditional method uses X-ray to visualize the bolus movement (video pharyngeography) + Because of the low price per channel many measuring points can be used (2 cm spacing) to cover the total esophagus

3 + Impedance is the electrical resistance measured with an alternating current + Impedance is the inverse of conductance (Imp = 1/Cond) + Impedance is measured in Ohm ( Ω ) – Low impedance many ions are moving – High impedance a few ions are moving Georg Simon Ohm

4 + In order to reduce the oxidation of the metal electrodes, an alternating current is used at 3.2 kHz + That means the Plus and Minus are changing 3200 times per second.

5 Ohm*cm (at 1 kHz) Gastric contents 30 – 100 Bile 90 Physiologic saline solution 100 Saliva 110 Skeletal muscle Milk / Yoghurt 300 Custard-based dessert / curds 400 Drinking water 1100 Cola 1100 Esophageal wall 2000 Epidermis 2000 – Air A.J.P.M. Smout, UMC-Utrecht, The Netherlands

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7 + Use a impedance catheter + A small electrical current is used to measure the impedance between the 2 rings Ring R1 R2 Patient safe low electrical current

8 + Catheters with multiple metal rings + A ring can be used for 2 channels if the distance is not too big (2 cm) Channel Ring R1 R2 R3 R4

9 Oesophagus wall Pressure contraction Water bolus Air in front of bolus Impedance ring Pressure sensor

10 + Baseline signal IMP PRES

11 + Air in front of the bolus IMP PRES

12 + Bolus IMP PRES

13 + Pressure contraction (increased impedance) IMP PRES

14 + Baseline signal IMP PRES

15 Baseline Air Bolus Contraction Baseline Bolus entry …. exit

16 Belching Baseline Air Baseline

17 + A Wet swallow: The liquid falls down into the esophagus + B The front of the pressure wave clears the esophagus 4 sec A B WS Clearing Peak Imp Pres

18 + Impedance + pH – Single use – pH antimony – Internal reference – 1 or 2 pH channels – 7 or 8 rings

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20 + BPT (Bolus Presence Time) – Time elapsed between: Bolus entry and Bolus exit using a 50% threshold. 50 % BPT

21 + BHAT (Bolus Head Advance Time) – Time elapsed between: Bolus entry at top channel and Bolus entry at each channel – Speed of bolus moving down BHAT

22 + TBTT (Total Bolus Transit Time) – Time elapsed between: Bolus entry at top channel and Bolus exit at lowest channel TBTT

23 + STT (Segment Transit Time) – Time elapsed between: Bolus entry at a channel and Bolus exit at next (lower) channel STT

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25 + Esophagus – bolus transit – gas transport (air swallowing and belching) – gastro-esophageal reflux

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28 Liquid swallows 80 % complete bolus transit Viscous swallows 70 % complete bolus transit Tutuian R et al. Clin Gastroenterol Hepatol 2003;1: healthy subjects solid-state manometry 10 liquid, 10 viscous swallows Normal esophageal transit when :

29 Manometric diagnosis N Normal transit Achalasia 24 0% Scleroderma 4 0% IEM 71 51% DES 33 55% Normal125 95% Hypertensive LES 25 96% Nutcracker 30 97% LES dysrelaxation 33100% Hypotensive LES 5100% IEM = Ineffective Esophageal Motility DES = Diffuse Esophageal Spasms

30 + 40 patients with non-obstructive dysphagia + Combined manometry+impedance + Manometry findings Impedance (transit findings) + Normal 20 35% abnormal transit + Ineffective motility % abnormal transit + Esophageal spasms 4 67 % abnormal transit + Achalasia % abnormal transit + total 40

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32 + Normal air intake during: – Dry swallow – Wet swallow – Food intake April

33 + Type I belches + Gastric belch – Normal venting of gastric air – After intake of CO 2 like Coca Cola April

34 + Type II belches + Supragastric belch – Sucking air into the esophagus with immediate expulsion – Aerophagia + [A] Suck air in + [B] Belch out April AB

35 + Manometry (=pressure waves) + Impedance (=transit) + Main indication: – (non-obstructive) Dysphagia – Belching – Clarify functional defects

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37 + Reflux of gastric content into the esophagus + Symptoms: heartburn / regurgitation + Damage to the esophageal wall (esophagitis) + Up to 10% of world population + Golden standard diagnostic tool: – 24 hr pH monitoring

38 + Reflux is acid which flows from the stomach into the esophagus + Detected with pH probe

39 April imp pH seconds pH>4 Non-acid reflux PAIN Reflux Non-acid reflux Weakly acidic reflux Not detected by pH probe but by impedance

40 + Reflux subcategories: – Acid reflux (pH falls below 4) – Super-imposed acid reflux (reflux while pH is already below 4) – Weakly acidic reflux (pH nadir >4 but <7) – Non-acid reflux (pH >7)

41 Off PPI On PPI 55% 97% Vela M et al. Gastroenterology 2001;120:

42 + Weakly acid reflux (pH >4) can cause symptoms + Most of the patients who visit a GI doctor continue to use PPI + Weakly acid reflux cannot be analysed with a pH probe + Impedance-pH detects ALL reflux episodes

43 + Gastric content is very often not acid due to milk intake. Sometimes even higher than pH 7 due to buffering + Reflux cannot be detected with a pH probe + Impedance recording – Bolus transit and reflux measured – Reflux contents does not matter – 24 hour (just like ambulatory pH)

44 + 17 Infants with regurgitation, asthma, apnea meals (milk) per day + Gastric pH often > 4 + Patient group: 17 children – 675 refluxes 185 acid 490 non-acid Skopnik et al, J. Pediatric Gastroenterol Nutr 1969

45 + Esophageal impedance monitoring can detect reflux with a pH above 4 – Weakly acid reflux + It can detects acid and non-acid reflux episodes + Clinical useful for evaluation of: – Symptoms under PPI – Symptoms off PPI – Unexplained cough – Pediatric practice April

46 April

47 April

48 + Ohmega specs – 8 to 13 Impedance rings – 1 to 4 pH Antimony – 2 glass pH – 2 ISFET pH (optional) – 4 pressure channels (optional) – Bluetooth wireless connection (up to 50 meter) – Memory 128 MB – USB interface with PC – Power supply 1 AA battery (recording time hr) April

49 + Data size ambulatory investigation 24 hr – 50 MB for 24 hours – Sample rate: 50 samples/sec impedance channels (6 channels) 1 sample/sec pH channel + MMS non destructive data compression 50 MB into 15 MB + Download time 5 – 10 minutes + Use CD-R or DVD-R as backup + Recording time 1 AA battery hr + Internal memory 2-3 days

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